It is known that oligoesters are used as soil release polymers in detergents and cleaners. These oligoesters are condensation products of dimethyl terephthalate, ethylene glycol, propylene glycol and polyalkylene glycols. As a consequence of a molar excess of the alcohol component, these oligoesters contain terminal OH groups which may, wholly or in part, be terminated by alkoxy groups (endcaps). Compounds of this type are available commercially under the names ®Milease T, ®Permalose, ®Repel-O-Tex. For more details, reference may be made to the specifications EP 185 427, EP 241 984, EP 241 985, EP 272 033, EP 757 468, EP 201 124, EP 253 567, GB 2 304 727, U.S. Pat. No. 4,116,885, U.S. Pat. No. 4,210,417, U.S. Pat. No. 3,962,152 and WO 92/17 523.